The present invention relates generally to panel display systems and more specifically to an improvement in the invention of U.S. Pat. No. 5,771,321, issued Jun. 23, 1998 entitled “Micromechanical optical switch and flat panel display” by Stern, the disclosure of which is specifically incorporated herein by reference.
As mentioned in the above-cited patent, electronically controlled optical displays, and particularly flat panel optical displays, which generally are distinguished by their relative slimness and ability to produce a direct, as opposed to a projected, display image are of increasing technological importance for a wide range of applications. Flat panel optical displays that produce directly viewable video images such as text and graphics are, in theory, ideally suited as television monitors, computer monitors, and other such display screen scenarios. Yet the many flat panel optical display approaches heretofore proposed and investigated all exhibit serious disadvantages that have limited their practical applicability as a commercially viable flat panel display screen technology.
For example, the class of flat panel displays known as liquid crystal displays require complex manufacturing processes that currently produce relatively low yields, resulting in an overall size limitation for volume production. In operation, liquid crystal displays require considerable power to maintain a display backlight and these displays provide only a limited range of viewing angles. Electroluminescent display technology suffers from similar limitations, as well as a limited display color range and limited operational lifecycle.
Active-matrix display technology, which employs an active electronic device at each pixel location of a display, is likewise limited both by high power consumption, production yield constraints, and limited operational lifecycle. Color gas plasma display technology, like liquid crystal technology, requires a complex manufacturing process to produce an optical display; a gas plasma display relies on complicated packaging schemes for providing reliable containment of a noble gas, resulting in high manufacturing costs.
Various electromechanical display technologies have been proposed which generally rely on electronic control in conjunction with manipulation of mechanical elements in a display.
The Micromechanical Optical Switch and Flat Panel Display patent provides for the controlled release of light that is trapped inside a flat transparent plate by contacting the surface with micromechanical elements. The optical intensity and color of a pixel can be established by a combination of area and temporal weighting; area weighting is accomplished by using multiple elements within a pixel, whereby the element areas are varied in a binary progression in order to extract light from within the transparent plate in a binary fashion.
Problem: As many as 2000 pixels/row are needed in a HDTV display, and if we use 3 area weights/color and 3 colors/pixel then as many as 18,000 binary drivers are needed. In large displays the driver count can double in order to drive the display from both top and bottom. Even if the cost of a driver circuit is reduced to a few cents, the total cost of the drive circuits alone could exceed $1000/display, which could make the concept unattractive in commercial markets.
The task of improving micromechanical flat panel display systems is alleviated, to some extent, by the following U.S. Patents, the disclosures of which are incorporated herein by reference:    U.S. Pat. No. 3,238,396 issued to Nelson et al.    U.S. Pat. No. 3,871,747 issued to Andrews    U.S. Pat. No. 4,087,810 issued to Hung et al.    U.S. Pat. No. 4,113,360 issued to Baur et al.    U.S. Pat. No. 4,234,361 issued to Guckel et al.
As mentioned in Sterns' previous patent, typical mechanical display schemes have been limited by so many manufacturing complexities and/or operational constraints that they are as yet commercially impractical. Furthermore, the speed, resolution, and power consumption requirements of the latest optical display applications have heretofore been unachievable by conventional electromechanical display technologies. But electronic as well as electromechanical display technologies have all required design and performance trade-offs resulting in one or more suboptimal manufacturing or operational considerations.